max2016etit Maxim Integrated Products, Inc., max2016etit Datasheet - Page 15

• Manufacturer Part Number: max2016etit
• Description: Max2016 Lf-to-2.5ghz Dual Logarithmic Detector/controller For Power, Gain, And Vswr Measurements
• Manufacturer: Maxim Integrated Products, Inc.

Controller for Power, Gain, and VSWR Measurements
Figure 7. In Power-Controller Mode, the DC Voltage at OUTA or
OUTB Controls the Gain of the PA, Leading to a Constant
Output Power Level (Note: Only one controller channel is
shown within the figure. Since the MAX2016 is a dual con-
troller/detector, the second channel can be easily implemented
by using the adjacent set of input and output connections.)
The MAX2016 can also be used as a power detector/
controller within an AGC loop. Figure 7 depicts a sce-
nario where the MAX2016 is employed as the AGC cir-
cuit. As shown in the figure, the MAX2016 monitors the
output of the PA through a directional coupler. An inter-
nal differencing amplifier (Figure 5) compares the
detected signal with a reference voltage determined by
V
es the voltage at OUT_, according to how closely the
detected signal level matches the V
MAX2016 maintains the power of the PA to a level
determined by the voltage applied to SET_.
Since the logarithmic detector responds to any ampli-
tude modulation being carried by the carrier signal, it
may be necessary to insert an external lowpass filter
between
(OUTA/OUTB) and the gain-control element to remove
this modulation signal.
SET_
TRANSMITTER
LOWPASS
FILTER
SET-POINT
. The differencing amplifier increases or decreas-
DAC
POWER AMPLIFIER
the
OUTA/
SETA/
OUTB
SETB
GAIN-CONTROL INPUT
______________________________________________________________________________________
differencing
20kΩ
20kΩ
LF-to-2.5GHz Dual Logarithmic Detector/
Power-Controller Mode
LOGARITHMIC
DETECTOR
MAX2016
amplifier
SET_
RFINA/
RFINB
reference. The
COUPLER
output
The transfer slope function of OUTA and OUTB can be
increased from its nominal value by varying resistors
R1 and R2 (see the Typical Application Circuit). The
equation controlling the slope is:
The transfer slope function of OUTD can be increased
from its nominal value by varying resistor R3 (see the
Typical Application Circuit). The equation controlling
the slope is:
The MAX2016 integrates a programmable highpass fil-
ter on each RF input. The lower cutoff frequency of the
MAX2016 can be decreased by increasing the external
capacitor value between FA1 and FA2 or FB1 and FB2.
By default, with no capacitor connecting FA1 and FA2
or FB1 and FB2, the lower cutoff frequency is 20MHz.
Using the following equation determines the lowest
operating frequency:
where R = 2Ω.
The bandwidth and response time difference of the out-
put amplifier can be controlled with the external capaci-
tor, C
external capacitor, the bandwidth is greater than 20MHz.
The following equation determines the bandwidth of the
amplifier difference:
where R = 1.8kΩ.
Use a video bandwidth lower than the anticipated low-
est amplitude-modulation frequency range to yield the
greatest accuracy in tracking the average carrier
power for high peak-to-average ratio waveforms.
SLOPE OUTA OR OUTB
15
, connected between FV1 and FV2. With no
SLOPE OUTD
OUTA and OUTB Slope Adjustment
Differential Output Video Filter
frequency
frequency
= −
OUTD Slope Adjustment
⎛
⎜
⎝
=
Input Highpass Filters
⎛
⎜
⎝
25
9
=
=
mV
dB
mV
dB
2π
2π
1
RC
⎞
⎟
⎠
1
RC
⎞
⎟
⎠
⎡
⎢
⎢
⎣
⎛
⎜
⎝
(
R or R
R
1
3 20
20
+
k
20
2
k
k
)
⎞
⎟
⎠
+
40
k
⎤
⎥
⎥
⎦
15